(1) Background: Swine hepatitis E (SHE) is an emerging zoonotic disease caused by the swine hepatitis E virus (SHEV). The open reading frame 3 (ORF3) protein is a recognized virulence factor of SHEV. Jaundice, the typical clinical sign of SHE, primarily results from disruptions in bile production, secretion, and excretion. However, the mechanism by which SHEV ORF3 influences bile metabolism remains unclear. (2) Methods: Building on our previous work involving adenovirus-mediated overexpression of genotype IV SHEV ORF3 in HepG2 cells and subsequent high-throughput lncRNA/transcriptome sequencing, this study performed KEGG enrichment analysis on differentially expressed lncRNAs. Candidate lncRNAs were validated via qRT-PCR. Cis-regulated target genes were predicted by integrating differentially expressed mRNA data. Furthermore, AlphaFold 3.0 was employed to analyze the molecular binding sites between lncRNA UBC (MSTRG.6881.4) and its target, UBC protein. (3) Results: We identified three lncRNAs associated with the bile secretion pathway (ko 04976) in HepG2 cells expressing genotype IV SHEV ORF3, which were further confirmed by qRT-PCR: lncRNA UBC (MSTRG.6881.4), lncRNA UBC (MSTRG.6881.9), and lncRNA UBC (MSTRG.6881.12). Bioinformatics prediction suggested six lncRNA-mRNA regulatory networks involved these lncRNAs and two downregulated UBC mRNA transcripts (ENST00000540700 and ENST00000536769). Molecular docking indicated that nucleotides 395U and 41C of lncRNA UBC (MSTRG.6881.4) could potentially bind to residues 82Lys, 88Thr, and 90Thr of the UBC protein, with predicted binding energies ranging from −4.73 to −0.75 kcal/mol. (4) Conclusions: The successful identification of bile secretion-related lncRNAs, coupled with the prediction of their regulatory networks and molecular interaction sites, has advanced our understanding of SHEV ORF3 function and the pathogenesis of SHEV infection.

The Swine hepatitis E virus (SHEV) ORF3 protein is pivotal in pathogenesis, yet its regulation of host metabolic homeostasis via endogenous RNA networks remains unclear. This study aimed to elucidate how the SHEV ORF3-mediated circRNA-miRNA network modulates riboflavin metabolism and triggers the aberrant activation of the ko05212 pathway, while also evaluating their physical interactions using AlphaFold 3 structural simulations. To achieve this, high-throughput RNA sequencing, KEGG pathway analysis, and AlphaFold 3 structural simulations were employed to elucidate the circRNA-miRNA-mRNA regulatory network and potential physical interactions. Transcriptomics revealed a “dual activation” of Riboflavin metabolism and Pancreatic cancer pathways. Specifically, we identified an “ENPP Isozyme Switch,” where upregulated hsa_circ_0077855 sponges miR-181a-2-3p, relieving repression of the metabolic enzyme ENPP3 and proto-oncogene KRAS. Furthermore, AlphaFold 3 simulations yielded an extremely low interface predicted Template Modeling score (ipTM = 0.08), refuting direct physical binding, and ORF3 was found to suppress the m6A eraser FTO, suggesting host epigenetic instability. Consequently, SHEV ORF3 induces metabolic remodeling through a dual “epigenetic-post-transcriptional” mechanism: disrupting m6A homeostasis via FTO suppression and constructing a pathogenic ceRNA network via the ENPP3/miR-181a/KRAS axis. These findings highlight the critical role of non-coding RNAs in driving the virus-induced “pre-pathological state”.

Background: The ORF3 protein of swine hepatitis E virus (HEV-4) is a key virulence factor involved in viral assembly, egress, and host signaling regulation. The mammalian target of rapamycin (mTOR) pathway plays a pivotal role in autophagy, metabolism, and immunity, and is often modulated by viruses to promote replication. However, it remains unknown whether HEV-4 ORF3 modulates the mTOR pathway via circular RNAs (circRNAs). Methods: Using an adenovirus-mediated ORF3 overexpression system in HepG2 cells, we integrated circRNA and transcriptome high-throughput sequencing data, followed by KEGG enrichment analysis to identify mTOR-associated differentially expressed genes. A circRNA–miRNA regulatory network was constructed using bioinformatics tools, and the expression changes of m6A-related genes, including YTHDF3, were evaluated. Results: ORF3 overexpression significantly activated the mTOR pathway (p < 0.05) and led to the identification of 20 mTOR-related circRNAs (e.g., circRNA5142). These circRNAs regulated downstream autophagy and lipid metabolism genes by sponging miRNAs such as hsa-let-7d-5p and hsa-miR-132-3p. Altered YTHDF3 expression indicated possible m6A-dependent epitranscriptomic regulation of the mTOR pathway. Conclusions: Our integrated analysis suggests that HEV-4 ORF3 may modulate the mTOR pathway through a circRNA–miRNA network, perturbing host autophagy and metabolic balance, which may contribute to viral immune evasion. Targeting the ORF3-mediated circRNA-mTOR regulatory axis represents a promising therapeutic approach and provides a theoretical basis for novel anti-HEV-4 strategies.